This application represents a joint application by six individuals for support to pursue a multidisciplinary study of membrane phenomena in excitable cells. With CORE SUPPORT, it is proposed to establish an electronic shop, expand a machine shop, establish a computer facility, collect and deliver squid to Baltimore, establish a central analytical facility, improve the performance of dialysis capillary. With individual RESEARCH SUPPORT, it is proposed to study: Squid axons: metabolism of divalent cations; Myxicola axons: ionic and electrical factors involved in excitability; Barnacle muscle fibers: divalent cation metabolism at rest and during mechanical activity. EXPERIMENTAL TECHNIQUES include voltage clamp analysis of membrane electrical events, fast time resolution of transmembrane ion flows, radioisotope studies of membrane transport, high sensitivity, fast time resolution measurements by dual wavelength spectroscopy of absorbance changes in ion specific dyes in cytoplasm and the use of the photoprotein, aequorin, for Ca measurements.